1. Field of the Invention
This invention relates generally to the field of power transmission belts, more particularly to rubber compositions suitable for belts, and specifically to a rubber composition reinforced with native kenaf fiber for use in belts.
2. Description of the Prior Art
Common power transmission belts include V-belts, flat belts, toothed or synchronous belts and multi-ribbed belts. Common belt construction includes an elastomeric belt body, spiraled or helically wound tension cord or other textile tensile member embedded in the belt body, and often other textile reinforcements embedded in the belt body or covering one or more of the belt surfaces.
The elastomeric belt body may include one or more vulcanized rubber composition, or a thermoplastic elastomer, or other elastomeric composition. Elastomer compositions used have included various fibrous reinforcements dispersed therein. Of the many fibers available, relatively few have found commercial success because of various processing and performance needs including excellent adhesion between fiber and elastomer, dispersibility, for wear and abrasion resistance, thermal resistance, environmental resistance, cost, reinforcement effect, and the like.
US 2010/0076118A1 discloses chemically modified microfibril cellulose for use in tire rubber, e.g., in natural rubber (NR), butadiene rubber (BR), styrene-butadiene rubber (SBR), and acrylonitrile butadiene rubber (NBR). Chemical modification of the microfibril cellulose is taught for improving dispersibility in the rubber and adhesion to the rubber in order to render it is useful. A method using the chemically modified microfibril cellulose in the form of a masterbatch prepared by complexing a rubber latex with the chemically modified microfibril cellulose in a water medium in advance is necessary in order to achieve good tensile characteristics and tire performance characteristics.
Kenaf has been suggested for biodegradable thermoplastic compositions. US 2006/0147695A1 discloses the use of kenaf bast fiber in crystalline thermoplastic resins such as polylactic acid resin for products such as electrical and electronic equipment. To improve the impact strength of the composition, it is taught to remove kenaf fragments before use or use a softening component or add a high strength impact resistant fiber. It is also taught that surface treatment of the kenaf fiber may be necessary to improve compatibility with the resin, impact resistance, and/or flame retardancy.
US 2005/0250931A1 discloses use of a long list of natural fibers including kenaf for increasing rigidity and impact strength of molded parts made from polylactic acid resin or parts based on recycled shredder dust thereof.
U.S. Pat. No. 6,663,733 discloses techniques for manufacturing synthetic resin-based products useful to form plate- or sheet-like products for use in vehicles. A ground plant product such as ground kenaf core product is taught in order to reduce specific gravity of the products.
Thus, the prior art fails to disclose or suggest a practical rubber composition for use in belts based on synthetic rubber reinforced with kenaf fiber.